Integrated desiccant-coated heat pump for air conditioning and battery thermal management in electric buses

With the growing demand for electric vehicles, improving battery stability and enhancing the energy efficiency of air conditioning (AC) systems have become increasingly important. This study introduces a desiccant coated heat pump (DCHP) system integrated with an AC unit and a battery thermal management system (BTMS) for electric buses. The proposed system directly coats desiccant on the evaporator and condenser surfaces, allowing independent temperature and humidity control. Numerical analyses validated by experiments demonstrated significant improvements in thermal performance. Under summer conditions, the system achieved a cooling coefficient of performance (COPc) of 5.92, representing a 110 % improvement over the conventional system, while providing a moisture removal capacity (MRC) of 10.8 g/kg without requiring a reheating process. In winter, the heating COP (COPh) reached 8.9, representing a 134 % improvement, with a moisture supply capacity (MSC) of 3.6 g/kg, thus maintaining humidity under dry ambient conditions. A parametric study highlighted the sensitivity of system performance to air velocity, half-cycle time, and evaporation/condensation temperatures, identifying optimal operating ranges for practical applications. The system maintained cell temperatures below 47 °C under extreme heat and achieved uniform preheating to 0 °C within 727s under extreme cold for battery management. These results confirm that the DCHP-based integrated system simultaneously ensures cabin comfort and battery stability, while reducing energy consumption compared to conventional approaches. The findings provide a foundation for advancing high-efficiency, multifunctional thermal management solutions in electric buses, supporting extended driving range, enhanced passenger comfort, and improved reliability in diverse climates.